Beaver Brook Road Bridge & Spillway Replacement

What Was the Challenge?

Sullivan County needed to replace the deteriorated Beaver Brook Road Bridge and associated dam spillway, a critical structure that provides the only outlet for Toasperns Pond. The existing spillway was significantly undersized, unable to pass the required spillway design flood, and contributed to the dam’s classification as a Class C/High Hazard structure rated “unsound” during its most recent inspection. Because the roadway embankment functions as the dam, and the bridge crosses over the dam spillway, the County faced both safety and regulatory pressures to replace the spillway with a longer, compliant structure while ensuring continued vehicular access by constructing a new bridge and maintaining traffic during construction.

How did Barton & Loguidice Provide a Solution?

Through a BridgeNY-funded effort, B&L completed detailed hydrologic and hydraulic modeling to determine the appropriate spillway length, ultimately increasing it from 40 to 90 feet. The spillway was relocated slightly upstream from its previous location and designed as an ogee shaped structure with a curved downstream face, an efficient configuration that improves hydraulic performance and rapidly passes flows over the dam. The new bridge was designed with bedrock-founded abutments and a metalized multi-steel girder superstructure to ensure durability and long-term resilience.

To maintain traffic access, B&L designed a temporary on-site detour bridge and roadway. The project also included preparation of a SWPPP, design of permanent stormwater treatment measures, coordination with NYSDEC Dam Safety for permitting and construction oversight, updates to dam regulatory documentation, and approximately 620 linear feet of roadway reconstruction, including proper superelevation, guide rail upgrades, and drainage improvements.

Why Was This Project a Success?

The project delivered a modern, hydraulically efficient spillway and robust bridge structure that brings the dam into compliance with NYSDEC regulations, improves public safety, and reduces the risk of overtopping during major storm events. Traffic impacts were minimized through strategic detour planning, and regulatory coordination ensured seamless approval and construction progress. The result is a safer, more resilient crossing that protects downstream communities and restores the structural integrity of a high-hazard dam and bridge structure.